Why does tiny San Juan County, population 720, have the fastest-growing over-65 population in the country?
Census data released Thursday shows the county's elderly population grew at a rate of 70.9 percent between 2010 and 2014. San Miguel County was right behind at 58.2 percent.
So, to return to the question, why?
One reason is obvious: the counties' small populations mean a relatively modest change in raw numbers can add up to big rate changes. In San Juan County, the 65+ population grew by just 61 people.
This map shows growth in 65+ population by county. Darker green indicates more growth; lighter means less.
The other cause has been in the works for decades.
"As amazing as it seems, John Denver had a huge influence," state demographer Elizabeth Garner said, referring to a big migration to the Western Slope in the 1960s and 1970s. The thousands of 20- and 30-somethings that were apparently moved by the folk singer to move to Colorado are now reaching retirement age, Garner said.
"It's people celebrating birthdays. Last year they were 64, this year they are 65," she said.
Thursday's data release is the latest indicator in a long-awaited senior boom in Colorado. Check out more coverage of aging in Colorado from Colorado Matters.